Wrist

True/False: The styloid process of the ulna extends more distally then the styloid process of radius

False; Styloid process of radius extends more distally

Serves as a pulley for EPL, ECRB, ED, IE tendons

Dorsal tubercle of Radius / Lister’s Tubercle

Angulations of the distal radius

1. Ulnar Tilt - 23 deg towards Ulna

2. Palmar / Volar Tilt - 11 degrees toward palm

Normal ulnar tilt of the distal radius

23 degrees towards the ulna

Normal volar tilt of the distal radius

11 degrees towards the palm

AKA navicular bone

Scaphoid

How many carpal bones does scaphoid come to contact with?

four carpal bones

Most commonly fractured carpal bone

Scaphoid

MOI of Scaphoid fracture

Wrist extended and radially deviated

The Scaphoid and lunate receives _____ of axial load

80% of axial load

True/False: the scaphoid is most mobile during abduction/adduction

False; Most mobile during flexion/extension

Most frequently dislocated carpal bone

Lunate

True/False: The lunate has least motion during flexion-extension

True

AKA triangular carpal bone

triquetrum

The only carpal bone with one articulating surface

Pisiform

What muscle attaches to the pisiform?

Flexor Carpi Ulnaris

AKA Greater Multangular

Trapezium

Trapezium and scaphoid forms the _____ of anatomic snuffbox

floor

AKA less multangular

Trapezoid

AKA Os Magnum

Capitate

Largest carpal bone

Capitate

True/False: The Scaphoid is the Axis of all wrist motion

False: Capitate

Keystone of the Wrist

Capitate

Articulating Surfaces for Radiocarpal joint

• PROXIMALLY: biconcave distal end of the radius and the radioulnar articular disc (part of triangular fibrocartilage complex; TFCC)

• DISTALLY: biconvex scaphoid, lunate and triquetrum

Articulating surfaces for Mid Carpal Joint

Between the proximal and distal row

• SCAPHOID TO TRAPEZIUM, TRAPEZOID, CAPITATE

• LUNATE TO CAPITATE

• TRIQUETRIUM TO HAMATE

What type of joint is the Radiocarpal joint

Synovial biaxial ellipsoid joint

What type of joint is the Transverse carpal joint

Synovial planar joint

Movements in the Radiocarpal joint

• Volar flexion → Hyperextension

• Radial (abduction) → ulnar (adduction) deviation

Movements in the Transverse Carpal joint

Gliding

Planes + Axis of Radiocarpal joint

• Sagittal Plane - X axis

• Frontal plane - Z axis

Planes + Axis of Midcarpal joint

None; Gliding movements

OPP of radiocarpal joint

Neutral, slight ulnar deviation

OPP of Midcarpal joint

Neutral, slight flexion and ulnar deviation

CPP of radiocarpal joint

Full extension, radial deviation

CPP of transverse carpal joint

Full extension

Radiocarpal Wrist flexion ROM

50 degrees

Radiocarpal Wrist extension ROM

35 degrees

Radiocarpal ulnar deviation ROM

2/3 of the motion

Radiocarpal Radial deviation

½ of the motion

Midcarpal Wrist Flexion ROM

35 degrees

Midcarpal joint wrist extension ROM

50 degrees

Midcarpal ulnar deviation ROM

1/3 of the motion

Midcarpal radial deviation ROM

½ of the motion

Arthrokinematics of Radiocarpal Joint

Opposite Roll and Glide

Arthrokinematics of Midcarpal joint

Opposite Roll and Glide

How many DoF does the midcarpal joint have

2; contributes to flex-ext & abd-add

Primary Muscles of Wrist Extension

• extensor carpi radialis longus

• extensor carpi radialis brevis

• extensor carpi ulnaris

Secondary Muscles of Wrist Extension

• Extensor Digitorum

• Extensor indicis

• Extensor digiti minimi

• Extensor pollicis longus

At 90 deg, this muscle can flex elbow if biceps and brachialis are paralyzed

Extensor carpi radialis longus

This muscle only acts as a wrist extensor only when the digits are simultaneously extended

Extensor Digitorum

Primary Movers of Wrist Flexion

• Flexor carpi radialis

• Flexor Carpi ulnaris

Secondary Wrist Flexors

• Palmaris longus

• Flexor digitorum profundus

• Flexor digitorum superficialis

• Flexor Pollicis Longus

• Abductor pollicis longus

Wrist Ulnar Deviators

• Extensor carpi ulnaris

• Flexor Carpi ulnaris

Primary Radial deviators

• Extensor carpi radialis longus

• Flexor Carpi ulnaris

Secondary Radial Deviators

1. Secondary (Houglum & Bertoti, 2012)

   • extensor pollicis brevis

   • abductor pollicis longus

2. Secondary (Levangie et al., 2019)

   • extensor indicis

   • flexor carpi radialis

   • flexor pollicis longus

Most important for wrist stability

Tension of ligaments

No muscles inserts on carpal except for ___________

flexor carpi ulnaris

Most Radial Deviation occurs at what joint? Why?

midcarpal joint; RD at RC at is limited as the radial side of the carpal impinge against the styloid process of the radius

Main function of the wrist extensors

Position and stabilize the wrist for activities involving the fingers

Most active wrist extensor during light closure

ECRB

Grip strength is reduced when the wrist is fully flexed because of 2 factors:

1. Finger extension is in passive insufficiency

2. Finger flexion is in active insufficiency

Order of muscle activation as grip force increases

ECU - ECRL - ECRB

At >15 elbow flexion, wrist extensor perform what action?

Elbow flexion